drivers/nble: Export bt_conn_lookup_handle()

bt_conn_lookup_handle() would be used in gatt.c to access conn's
discovery parameters.

Change-Id: Ibb494cf8af90ccab478fa7463a41942b06029539
Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>

drivers/nble/conn.h

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+struct bt_conn *bt_conn_lookup_handle(uint16_t handle);